Electromagnetic wave detection apparatus and information acquisition system

ABSTRACT

An electromagnetic wave detection apparatus ( 10 ) includes a separation unit ( 16 ), a first detector ( 17 ), a switch ( 18 ), and a second detector ( 20 ). The separation unit ( 16 ) separates incident electromagnetic waves so that the electromagnetic waves propagate in a first direction (d 1 ) and a second direction (d 2 ). The first detector ( 17 ) detects the electromagnetic waves that propagate in the first direction (d 1 ). The switch ( 18 ) includes a plurality of switching elements (se). The switching elements (se) are capable of switching the propagation direction of the electromagnetic waves that propagate in the second direction (d 2 ) to a third direction (d 3 ) and a fourth direction (d 4 ). The second detector ( 20 ) detects the electromagnetic waves that propagate in the third direction (d 3 ).

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and the benefit of JapanesePatent Application No. 2017-103942 filed May 25, 2017, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electromagnetic wave detectionapparatus and an information acquisition system.

BACKGROUND

In recent years, apparatuses have been developed to acquire informationrelated to the surroundings from the results of detection by a pluralityof detectors that detect electromagnetic waves. For example, anapparatus that uses laser radar to measure the position of an object inan image captured by an infrared camera is known, as in patentliterature (PTL) 1.

CITATION LIST Patent Literature

PTL 1: JP2011-220732A

SUMMARY

An electromagnetic wave detection apparatus according to a firstembodiment includes:

a separation unit configured to separate electromagnetic waves incidenton the separation unit so that the electromagnetic waves propagate in afirst direction and a second direction;

a first detector configured to detect the electromagnetic waves thatpropagate in the first direction;

a switch including a plurality of switching elements capable ofswitching a propagation direction of the electromagnetic waves thatpropagate in the second direction to a third direction and a fourthdirection; and

a second detector configured to detect the electromagnetic waves thatpropagate in the third direction.

An information acquisition system according to an embodiment includes:

an electromagnetic wave detection apparatus comprising a separation unitconfigured to separate electromagnetic waves incident on the separationunit so that the electromagnetic waves propagate in a first directionand a second direction, a first detector configured to detect theelectromagnetic waves that propagate in the first direction, a switchcomprising a plurality of switching elements capable of switching apropagation direction of the electromagnetic waves that propagate in thesecond direction to a third direction and a fourth direction, and asecond detector configured to detect the electromagnetic waves thatpropagate in the third direction; and

a controller configured to acquire information related to surroundingsof the electromagnetic wave detection apparatus based on anelectromagnetic wave detection result by the first detector and thesecond detector.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a configuration diagram schematically illustrating aninformation acquisition system that includes an electromagnetic wavedetection apparatus according to a first embodiment;

FIG. 2 is a state diagram of the information acquisition system toillustrate the propagation direction of electromagnetic waves in a firststate and a second state of switching elements in a switch of theelectromagnetic wave detection apparatus of FIG. 1;

FIG. 3 is a timing chart of the timing of emission and detection ofelectromagnetic waves to illustrate the principle of ranging by aranging sensor configured by an irradiator, a second detector, and acontroller of FIG. 1;

FIG. 4 is a configuration diagram schematically illustrating anelectromagnetic wave detection apparatus according to a secondembodiment;

FIG. 5 is a state diagram of the electromagnetic wave detectionapparatus to illustrate the state of switching, by switching element,the propagation direction of electromagnetic waves in the secondembodiment; and

FIG. 6 is a configuration diagram schematically illustrating theconfiguration of a modification to the electromagnetic wave detectionapparatus according to the first embodiment.

DETAILED DESCRIPTION

Embodiments of an electromagnetic wave detection apparatus to which thepresent disclosure is applied are described below with reference to thedrawings. In a configuration for detecting electromagnetic waves with aplurality of detectors that each detect electromagnetic waves, thedetection axis of each detector differs. Therefore, even if eachdetector detects electromagnetic waves in the same region, thecoordinate system of the detection results differs between detectors. Itwould be helpful to reduce the difference between coordinate systems inthe detection results of the detectors. It is difficult or impossible,however, to reduce this difference by correction. The electromagneticwave detection apparatus to which the present disclosure is appliedreduces the difference between coordinate systems in the detectionresults of detectors by being configured to reduce the differencebetween the detection axes of the detectors.

As illustrated in FIG. 1, an information acquisition system 11 thatincludes an electromagnetic wave detection apparatus 10 according to afirst embodiment of the present disclosure is configured to include theelectromagnetic wave detection apparatus 10, an irradiator 12, areflector 13, and a controller 14.

In the drawings described below, the dashed lines connecting functionalblocks indicate the flow of control signals or communicated information.The communication represented by the dashed lines may be wiredcommunication or wireless communication. The solid lines projecting fromeach functional block indicate beams of electromagnetic waves.

The electromagnetic wave detection apparatus 10 includes a pre-stageoptical system 15, a separation unit 16, a first detector 17, a switch18, a first post-stage optical system 19, and a second detector 20.

The pre-stage optical system 15 includes either or both of a lens and amirror, for example, and forms an image of an object ob that becomes asubject of imaging.

The separation unit 16 is provided between the pre-stage optical system15 and a primary image formation position, which is the position wherethe image of the object ob located at a predetermined position separatefrom the pre-stage optical system 15 is formed by the pre-stage opticalsystem 15. The separation unit 16 separates incident electromagneticwaves so that the electromagnetic waves propagate in a first directiond1 and a second direction d2.

In the first embodiment, the separation unit 16 reflects a portion ofthe incident electromagnetic waves in the first direction d1 andtransmits another portion of the electromagnetic waves in the seconddirection d2. The separation unit 16 may transmit a portion of theincident electromagnetic waves in the first direction d1 and reflectanother portion of the electromagnetic waves in the second direction d2.The separation unit 16 may also refract a portion of the incidentelectromagnetic waves in the first direction d1 and refract anotherportion of the electromagnetic waves in the second direction d2. Theseparation unit 16 is, for example, a one-way mirror, a beam splitter, adichroic mirror, a cold mirror, a hot mirror, a metasurface, adeflection element, a prism, or the like.

The first detector 17 is provided along the path over whichelectromagnetic waves propagate from the separation unit 16 in the firstdirection d1. Furthermore, the first detector 17 is provided at or nearan image formation position, which is a position in the first directiond1 from the separation unit 16 where the image of the object ob locatedat a predetermined position separate from the pre-stage optical system15 is formed by the pre-stage optical system 15. The first detector 17detects the electromagnetic waves that propagate from the separationunit 16 in the first direction d1.

The first detector 17 may be disposed with respect to the separationunit 16 so that a first propagation axis of electromagnetic wavespropagating from the separation unit 16 in the first direction d1 isparallel to a first detection axis of the first detector 17. The firstpropagation axis is the central axis of the electromagnetic waves thatpropagate from the separation unit 16 in the first direction d1 whilespreading radially. In the first embodiment, the first propagation axisis bent so that the optical axis of the pre-stage optical system 15reaches the separation unit 16 and becomes parallel to the firstdirection d1 at the separation unit 16. The first detection axis passesthrough the center of the detection surface of the first detector 17 andis perpendicular to the detection surface.

Furthermore, the first detector 17 may be disposed so that the intervalbetween the first propagation axis and the first detection axis is equalto or less than a first interval threshold. The first detector 17 may bedisposed so that the first propagation axis and the first detection axiscoincide. In the first embodiment, the first detector 17 is disposed sothat the first propagation axis and the first detection axis coincide.

The first detector 17 may be disposed relative to the separation unit 16so that a first angle between the first propagation axis and thedetection surface of the first detector 17 is equal to or less than afirst angle threshold or is a predetermined angle. In the firstembodiment, the first detector 17 is disposed so that the first angle is90°, as described above.

In the first embodiment, the first detector 17 is a passive sensor. Ingreater detail, the first detector 17 in the first embodiment includes adevice array. For example, the first detector 17 includes an imagingdevice such as an image sensor or an imaging array, captures the imageformed from electromagnetic waves at a detection surface, and generatesimage information corresponding to the imaged object ob.

In greater detail, the first detector 17 in the first embodimentcaptures a visible light image. The first detector 17 transmits thegenerated image information to the controller 14 as a signal.

The first detector 17 may capture an image other than a visible lightimage, such as an image of infrared rays, ultraviolet rays, or radiowaves. The first detector 17 may include a ranging sensor. In thisconfiguration, the electromagnetic wave detection apparatus 10 canacquire distance information in image form with the first detector 17.The first detector 17 may include a ranging sensor thermosensor or thelike. In this configuration, the electromagnetic wave detectionapparatus 10 can acquire temperature information in image form with thefirst detector 17.

The switch 18 is provided along the path over which electromagneticwaves propagate from the separation unit 16 in the second direction d2.Furthermore, the switch 18 is provided at or near a primary imageformation position, which is a position in the second direction d2 fromthe separation unit 16 where the image of the object ob located at apredetermined position separate from the pre-stage optical system 15 isformed by the pre-stage optical system 15.

In the first embodiment, the switch 18 is provided at the imageformation position. The switch 18 has an action surface as on whichelectromagnetic waves that pass through the pre-stage optical system 15and the separation unit 16 are incident. The action surface as is formedby a plurality of switching elements se aligned two-dimensionally. Theaction surface as is a surface that, in at least one of the first stateand the second state described below, produces effects on theelectromagnetic waves such as reflection and transmission.

The switch 18 can switch each switching element se between a first stateof propagating the electromagnetic waves incident on the action surfaceas in a third direction d3 and a second state of propagating theelectromagnetic waves in a fourth direction d4. In the first embodiment,the first state is a first reflecting state of reflecting theelectromagnetic waves incident on the action surface as in the thirddirection d3. The second state is a second reflecting state ofreflecting the electromagnetic waves incident on the action surface asin the fourth direction d4.

In greater detail, the switch 18 of the first embodiment includes areflecting surface that reflects the electromagnetic waves on eachswitching element se. The switch 18 switches each switching element sebetween the first reflecting state and the second reflecting state bychanging the orientation of the reflecting surface of each switchingelement se.

In the first embodiment, the switch 18 includes a digital micro mirrordevice (DMD), for example. The DMD can drive minute reflecting surfacesthat configure the action surface as to switch the reflecting surface oneach switching element se between inclined states of +12° and −12°relative to the action surface as. The action surface as is parallel tothe board surface of a substrate on which the minute reflecting surfacesare mounted in the DMD.

The switch 18 switches each switching element se between the first stateand the second state based on control by the controller 14, describedbelow. For example, as illustrated in FIG. 2, the switch 18 cansimultaneously cause electromagnetic waves incident on a portion ofswitching elements se1 to propagate in the third direction d3 byswitching the switching elements se1 to the first state and causeelectromagnetic waves incident on another portion of switching elementsse2 to propagate in the fourth direction d4 by switching the switchingelements se2 to the second state.

As illustrated in FIG. 1, the first post-stage optical system 19 isprovided in the third direction d3 from the switch 18. The firstpost-stage optical system 19 includes either or both of a lens and amirror, for example. The first post-stage optical system 19 forms animage of the object ob represented by the electromagnetic waves whosepropagation direction is switched at the switch 18.

The second detector 20 is provided along the path of electromagneticwaves that propagate through the first post-stage optical system 19after propagating in the third direction d3 from the switch 18. Thesecond detector 20 detects electromagnetic waves that pass through thefirst post-stage optical system 19, i.e. electromagnetic waves thatpropagate in the third direction d3.

Along with the switch 18, the second detector 20 may be disposed withrespect to the separation unit 16 so that a second propagation axis ofelectromagnetic waves propagating from the separation unit 16 in thesecond direction d2 and switched in propagation direction to the thirddirection d3 by the switch 18 is parallel to a second detection axis ofthe second detector 20. The second propagation axis is the central axisof the electromagnetic waves that propagate from the switch 18 in thethird direction d3 while spreading radially. In the first embodiment,the second propagation axis is bent so that the optical axis of thepre-stage optical system 15 reaches the switch 18 and becomes parallelto the third direction d3 at the switch 18. The second detection axispasses through the center of the detection surface of the seconddetector 20 and is perpendicular to the detection surface.

Along with the switch 18, the second detector 20 may also be disposed sothat the interval between the second propagation axis and the seconddetection axis is equal to or less than a second interval threshold. Thesecond interval threshold may be the same as or different from the firstinterval threshold. Along with the first detector 17 and the switch 18,the second detector 20 may be disposed so that the interval between thefirst propagation axis and the first detection axis differs from theinterval between the second propagation axis and the second detectionaxis by a predetermined interval difference or less (for example, thediameter of the detection surfaces of the first detector 17 and thesecond detector 20). The second detector 20 may be disposed so that thesecond propagation axis and the second detection axis coincide. In thefirst embodiment, the second detector 20 is disposed so that the secondpropagation axis and the second detection axis coincide.

Along with the switch 18, the second detector 20 may be disposedrelative to the separation unit 16 so that a second angle between thesecond propagation axis and the detection surface of the second detector20 is equal to or less than a second angle threshold or is apredetermined angle. The second angle threshold may be the same as ordifferent from the first angle threshold. Along with the first detector17 and the switch 18, the second detector 20 may be disposed so that thedifference between the first angle and the second angle is equal to orless than a predetermined angle difference (for example, to satisfy theScheimpflug principle). In the first embodiment, the second detector 20is disposed so that the second angle is 90°, as described above.

In the first embodiment, the second detector 20 is an active sensor thatdetects reflected waves, from the object ob, of electromagnetic wavesirradiated towards the object ob from the irradiator 12. The seconddetector 20 in the first embodiment detects reflected waves, from theobject ob, of electromagnetic waves irradiated towards the object obafter being irradiated from the irradiator 12 and reflected by thereflector 13. As described below, the electromagnetic waves irradiatedfrom the irradiator 12 are at least one of infrared rays, visible lightrays, ultraviolet rays, and radio waves, and the second detector 20detects the same or a different type of electromagnetic waves as thefirst detector 17.

In greater detail, the second detector 20 of the first embodimentincludes a device configured as a ranging sensor. For example, thesecond detector 20 includes a single device such as an avalanchephotodiode (APD), a photodiode (PD), or a ranging image sensor. Thesecond detector 20 may include a device array, such as an APD array, aPD array, a ranging imaging array, or a ranging image sensor.

The second detector 20 of the first embodiment transmits detectioninformation, indicating the detection of reflected waves from thesubject, to the controller 14 as a signal. In greater detail, the seconddetector 20 detects electromagnetic waves in the infrared light band.

It suffices for the single device configured as the above-describedranging sensor in the second detector 20 to be capable of detectingelectromagnetic waves. Image formation at the detection surface is notrequired. The second detector 20 therefore need not be provided at asecondary image formation position, which is a position of imageformation by the first post-stage optical system 19. In other words, aslong as electromagnetic waves from all angles of view can be incident onthe detection surface, the second detector 20 with this configurationmay be disposed at any position along the path of electromagnetic wavesthat propagate in the third direction d3, due to the switch 18, andsubsequently pass through the first post-stage optical system 19.

The irradiator 12 emits at least one of infrared rays, visible lightrays, ultraviolet rays, and radio waves. In the first embodiment, theirradiator 12 emits infrared rays. The irradiator 12 irradiates theelectromagnetic waves towards the object ob either indirectly via thereflector 13 or directly. In the first embodiment, the irradiator 12irradiates the electromagnetic waves towards the object ob indirectlyvia the reflector 13.

In the first embodiment, the irradiator 12 emits a narrow beam, forexample 0.5°, of electromagnetic waves. In the first embodiment, theirradiator 12 emits pulses of electromagnetic waves. For example, theirradiator 12 includes a light emitting diode (LED), laser diode (LD),or the like. The irradiator 12 switches between emitting and notemitting electromagnetic waves based on control by the controller 14,described below.

The reflector 13 changes the irradiation position of electromagneticwaves irradiated onto the object ob by reflecting the electromagneticwaves emitted from the irradiator 12 while the orientation of thereflector 13 changes. In other words, the reflector 13 scans the objectob with the electromagnetic waves emitted from the irradiator 12.Accordingly, the second detector 20 in the first embodiment workstogether with the reflector 13 to form a scanning-type ranging sensor.The reflector 13 scans the object ob one- or two-dimensionally. In thefirst embodiment, the reflector 13 scans the object obtwo-dimensionally.

The reflector 13 is configured so that at least a portion of anirradiation region of the electromagnetic waves that are emitted by theirradiator 12 and reflected is included in an electromagnetic wavedetection range of the electromagnetic wave detection apparatus 10.Accordingly, at least a portion of the electromagnetic waves irradiatedonto the object ob via the reflector 13 can be detected by theelectromagnetic wave detection apparatus 10.

In the first embodiment, the reflector 13 is configured so that at leasta portion of the irradiation region of the electromagnetic waves thatare emitted by the irradiator 12 and reflected by the reflector 13 isincluded in the detection range of the second detector 20. Accordingly,in the first embodiment, at least a portion of the electromagnetic wavesirradiated onto the object ob via the reflector 13 can be detected bythe second detector 20.

The reflector 13 may, for example, include a micro electro mechanicalsystems (MEMS) mirror, a polygon mirror, a galvano mirror, or the like.In the first embodiment, the reflector 13 includes a MEMS mirror.

Based on control by the controller 14, described below, the reflector 13changes the direction in which electromagnetic waves are reflected. Thereflector 13 may include an angle sensor, such as an encoder, and maynotify the controller 14 of the angle detected by the angle sensor asinformation on the direction in which electromagnetic waves arereflected (direction information). This configuration allows thecontroller 14 to calculate the irradiation position based on thedirection information acquired from the reflector 13. The controller 14can also calculate the irradiation position based on a drive signalinputted to the reflector 13 to change the direction in whichelectromagnetic waves are reflected.

The controller 14 includes one or more processors and a memory. The term“processor” encompasses either or both general-purpose processors thatexecute particular functions by reading particular programs anddedicated processors that are specialized for particular processing. Thededicated processor may include an application specific integratedcircuit (ASIC). The processor may include a programmable logic device(PLD). The PLD may include a field-programmable gate array (FPGA). Thecontroller 14 may include either or both of a system-on-a-chip (SoC)that has one processor or a plurality of processors working together anda system-in-a-package (SiP).

The controller 14 acquires information related to the surroundings ofthe electromagnetic wave detection apparatus 10 based on electromagneticwaves detected by each of the first detector 17 and the second detector20. The information related to the surroundings may, for example, beimage information, distance information, and temperature information. Inthe first embodiment, the controller 14 acquires image information inthe form of electromagnetic waves detected as an image by the firstdetector 17, as described above. Based on the detection informationdetected by the second detector 20, the controller 14 in the firstembodiment also uses the time-of-flight (TOF) method to acquire distanceinformation of the irradiation position irradiated by the irradiator 12.

As illustrated in FIG. 3, the controller 14 causes the irradiator 12 toemit pulses of electromagnetic waves by inputting an electromagneticwave emission signal to the irradiator 12 (see the “electromagnetic waveemission signal” section). The irradiator 12 irradiates electromagneticwaves based on the inputted electromagnetic wave emission signal (seethe “irradiator emission amount” section). The electromagnetic wavesemitted by the irradiator 12 and reflected by the reflector 13 to beirradiated on an arbitrary irradiation region are reflected in theirradiation region. The controller 14 switches at least a portion of theswitching elements se, in an image formation region in the switch 18where reflected waves in the irradiation region are formed into an imageby the pre-stage optical system 15, to the first state and switches theother switching elements se to the second state. The second detector 20then notifies the controller 14 of detection information, as describedabove, when detecting electromagnetic waves reflected in the irradiationregion (see the “electromagnetic wave detection amount” section).

The controller 14 may, for example, include a time measurement largescale integrated circuit (LSI) and measure a time ΔT from a timing T1 atwhich the controller 14 caused the irradiator 12 to emit electromagneticwaves to a timing T2 at which the controller 14 acquires the detectioninformation (see the “detection information acquisition” section). Thecontroller 14 multiplies the time ΔT by the speed of light and dividesby two to calculate the distance to the irradiation position. Asdescribed above, the controller 14 calculates the irradiation positionbased on the direction information acquired from the reflector 13 or thedrive signal that the controller 14 outputs to the reflector 13. Bychanging the irradiation position while calculating the distance to eachirradiation position, the controller 14 creates distance information inimage form.

In the first embodiment, the information acquisition system 11 isconfigured to create distance information by direct ToF, in which thetime is measured from when laser light is irradiated until the laserlight returns, as described above. The information acquisition system 11is not, however, limited to this configuration. For example, theinformation acquisition system 11 may create distance information byflash ToF, in which electromagnetic waves are irradiated with a constantperiod, and the time until return is measured indirectly from the phasedifference between the irradiated electromagnetic waves and thereturning electromagnetic waves. The information acquisition system 11may also create distance information by another ToF method, such asphased ToF.

The electromagnetic wave detection apparatus 10 of the first embodimentwith the above configuration separates incident electromagnetic waves sothat the electromagnetic waves propagate in the first direction d1 andthe second direction d2 and can switch the propagation direction of theelectromagnetic waves that propagate in the second direction d2 to thethird direction d3. This configuration allows the electromagnetic wavedetection apparatus 10 to match the optical axis of the pre-stageoptical system 15 to the first propagation axis, which is the centralaxis of the electromagnetic waves propagated in the first direction d1,and to the second propagation axis, which is the central axis of theelectromagnetic waves propagated in the third direction d3. Theelectromagnetic wave detection apparatus 10 can therefore reduce themisalignment of the optical axes of the first detector 17 and the seconddetector 20. The electromagnetic wave detection apparatus 10 can therebyreduce the misalignment between the first detection axis and the seconddetection axis. Hence, the electromagnetic wave detection apparatus 10can reduce the misalignment of coordinate systems in the detectionresults of the first detector 17 and the second detector 20. The effectsof such a configuration are the same for the electromagnetic wavedetection apparatus of the second embodiment, described below.

In the electromagnetic wave detection apparatus 10 of the firstembodiment, the first detector 17, the switch 18, and the seconddetector 20 are disposed relative to the separation unit 16 so that thefirst propagation axis becomes parallel to the first detection axis, andthe second propagation axis becomes parallel to the second detectionaxis. This configuration allows the electromagnetic wave detectionapparatus 10 to reduce the misalignment between the first detection axisand the second detection axis and also achieve a uniform imaging stateof electromagnetic waves on the detection surface, regardless ofdistance from the propagation axis. Accordingly, the electromagneticwave detection apparatus 10 can obtain information related to thesurroundings in a uniform imaging state without performing informationprocessing in the controller 14 to achieve a uniform imaging state. Theeffects of such a configuration are the same for the electromagneticwave detection apparatus of the second embodiment, described below.

In the electromagnetic wave detection apparatus 10 of the firstembodiment, the first detector 17 is disposed relative to the separationunit 16 so that the interval between the first propagation axis and thefirst detection axis is equal to or less than the first intervalthreshold, and the switch 18 and second detector 20 are disposedrelative to the separation unit 16 so that the interval between thesecond propagation axis and the second detection axis is equal to orless than the second interval threshold. This configuration allows theelectromagnetic wave detection apparatus 10 to reduce the misalignmentbetween the first detection axis and the second detection axis further.The effects of such a configuration are the same for the electromagneticwave detection apparatus of the second embodiment, described below.

In the electromagnetic wave detection apparatus 10 of the firstembodiment, the first detector 17, the switch 18, and the seconddetector 20 are disposed relative to the separation unit 16 so that theinterval between the first propagation axis and the first detection axisdiffers from the interval between the second propagation axis and thesecond detection axis by a predetermined interval difference or less.This configuration allows the electromagnetic wave detection apparatus10 to reduce the misalignment between the first detection axis and thesecond detection axis even further. The effects of such a configurationare the same for the electromagnetic wave detection apparatus of thesecond embodiment, described below.

In the electromagnetic wave detection apparatus 10 of the firstembodiment, the first detector 17, the switch 18, and the seconddetector 20 are disposed relative to the separation unit 16 so that thefirst propagation axis coincides with the first detection axis, and thesecond propagation axis coincides with the second detection axis. Thisconfiguration allows the electromagnetic wave detection apparatus 10 toreduce the misalignment between the first detection axis and the seconddetection axis even further still. The effects of such a configurationare the same for the electromagnetic wave detection apparatus of thesecond embodiment, described below.

In the electromagnetic wave detection apparatus 10 of the firstembodiment, the first detector 17, the switch 18, and the seconddetector 20 are disposed relative to the separation unit 16 so that thefirst angle is equal to or less than the first angle threshold or is apredetermined angle, and so that the second angle is equal to or lessthan the second angle threshold or is a predetermined angle. Thisconfiguration allows the electromagnetic wave detection apparatus 10 toreduce the misalignment between the first detection axis and the seconddetection axis and also reduce the unevenness, corresponding to thedistance from the propagation axis, of the imaging state ofelectromagnetic waves on the detection surface. Accordingly, theelectromagnetic wave detection apparatus 10 can reduce the burden on thecontroller 14 for information processing to achieve a uniform imagingstate. The effects of such a configuration are the same for theelectromagnetic wave detection apparatus of the second embodiment,described below.

In the electromagnetic wave detection apparatus 10 of the firstembodiment, the first detector 17, the switch 18, and the seconddetector 20 are disposed relative to the separation unit 16 so that thedifference between the first angle and the second angle is equal to orless than a predetermined angle difference. This configuration allowsthe electromagnetic wave detection apparatus 10 to reduce themisalignment between the optical axes of the first detector 17 and thesecond detector 20 even further. The effects of such a configuration arethe same for the electromagnetic wave detection apparatus of the secondembodiment, described below.

The electromagnetic wave detection apparatus 10 of the first embodimentcan switch a portion of the switching elements se in the switch 18 tothe first state and switch another portion of the switching elements seto the second state. This configuration allows the electromagnetic wavedetection apparatus 10 to detect, using the second detector 20,information based on the electromagnetic waves at each portion of theobject ob that emits the electromagnetic waves incident on the switchingelements se. The effects of such a configuration are the same for theelectromagnetic wave detection apparatus of the second embodiment,described below.

Next, an electromagnetic wave detection apparatus according to a secondembodiment of the present disclosure is described. The second embodimentdiffers from the first embodiment by further including a third detector.The second embodiment is described below, focusing on the differencesfrom the first embodiment. The same reference signs are used forcomponents with the same configuration as in the first embodiment.

As illustrated in FIG. 4, an electromagnetic wave detection apparatus100 according to the second embodiment includes a pre-stage opticalsystem 15, a separation unit 16, a first detector 17, a switch 180, afirst post-stage optical system 19, a second post-stage optical system210, a second detector 20, and a third detector 220. The configurationof the information acquisition system 11 according to the secondembodiment other than the electromagnetic wave detection apparatus 100is the same as in the first embodiment. The configuration and functionsof the pre-stage optical system 15, the separation unit 16, the firstdetector 17, the first post-stage optical system 19, and the seconddetector 20 in the second embodiment are the same as in the firstembodiment.

The arrangement of the switch 180 in the electromagnetic wave detectionapparatus 100 is the same as in the first embodiment. Like the firstembodiment, the switch 180 includes an action surface as formed by aplurality of switching elements se aligned two-dimensionally. Unlike thefirst embodiment, the switch 180 can switch each switching element senot only to a first state of propagating the electromagnetic wavesincident on the action surface as in a third direction d3 and a secondstate of propagating the electromagnetic waves in a fourth direction d4,but also to a third state of propagating the electromagnetic waves in adirection other than the third direction d3 and the fourth direction d4.

In the second embodiment, the first state is a first reflecting state ofreflecting the electromagnetic waves incident on the action surface asin the third direction d3. The second state is a second reflecting stateof reflecting the electromagnetic waves incident on the action surfaceas in the fourth direction d4. The third state is a third reflectingstate of reflecting the electromagnetic waves incident on the actionsurface as in a direction other than the third direction d3 and thefourth direction d4.

In greater detail, the switch 180 of the second embodiment includes areflecting surface that reflects the electromagnetic waves on eachswitching element se. The switch 180 switches each switching element seamong the first reflecting state, the second reflecting state, and thethird reflecting state by changing the orientation of the reflectingsurface of each switching element se.

In the second embodiment, the switch 180 includes a digital micro mirrordevice (DMD), for example. The DMD can drive minute reflecting surfacesthat configure the action surface as to switch the reflecting surface oneach switching element se between inclined states of +12° and −12°relative to the action surface as. Furthermore, by suspending driving ofthe reflecting surface, the DMD can switch the reflecting surface ofeach switching element se to an inclined state of approximately 0°relative to the action surface as.

The switch 180 switches each switching element se among the first state,the second state, and the third state based on control by the controller14. For example, as illustrated in FIG. 5, the switch 180 cansimultaneously switch a portion of the switching elements se1 to thefirst state, another portion of the switching elements se2 to the secondstate, and the remaining switching elements se3 to the third state topropagate the electromagnetic waves incident on the switching elementsse1 in the third direction d3, the electromagnetic waves incident on theswitching elements se2 in the fourth direction d4, and theelectromagnetic waves incident on the switching elements se3 in adirection other than the third direction d3 and the fourth direction d4.

The second post-stage optical system 210 is provided in the fourthdirection d4 from the switch 180. The second post-stage optical system210 includes either or both of a lens and a mirror, for example. Thesecond post-stage optical system 210 forms an image of the object obrepresented by the electromagnetic waves whose propagation direction isswitched at the switch 180.

The third detector 220 is provided along the path of electromagneticwaves that propagate through the second post-stage optical system 210after propagating in the fourth direction d4 from the switch 180. Thethird detector 220 detects electromagnetic waves that pass through thesecond post-stage optical system 210, i.e. electromagnetic waves thatpropagate in the fourth direction d4.

Along with the switch 180, the third detector 220 may disposed withrespect to the separation unit 16 so that a third propagation axis ofelectromagnetic waves propagating from the separation unit 16 in thesecond direction d2 and switched in propagation direction to the fourthdirection d4 by the switch 180 is parallel to a third detection axis ofthe third detector 220. The third propagation axis is the central axisof the electromagnetic waves that propagate from the switch 180 in thefourth direction d4 while spreading radially. In the second embodiment,the third propagation axis is bent so that the optical axis of thepre-stage optical system 15 reaches the switch 180 and becomes parallelto the fourth direction d4 at the switch 180. The third detection axispasses through the center of the detection surface of the third detector220 and is perpendicular to the detection surface.

Along with the switch 180, the third detector 220 may also be disposedso that the interval between the third propagation axis and the thirddetection axis is equal to or less than a third interval threshold. Thethird interval threshold may be the same as or different from the firstinterval threshold the second interval threshold. Along with the firstdetector 17, the switch 180, and the second detector 20, the thirddetector 220 may be disposed so that the interval between the firstpropagation axis and the first detection axis and the interval betweenthe second propagation axis and the second detection axis differ fromthe interval between the third propagation axis and the third detectionaxis by a predetermined interval difference or less. The third detector220 may be disposed so that the third propagation axis and the thirddetection axis coincide. In the second embodiment, the third detector220 is disposed so that the third propagation axis and the thirddetection axis coincide.

Along with the switch 180, the third detector 220 may be disposedrelative to the separation unit 16 so that a third angle between thethird propagation axis and a perpendicular to the detection surface ofthe third detector 220 is equal to or less than a third angle thresholdor a predetermined angle. The third angle threshold may be the same asor different from the first angle threshold or the second anglethreshold. Along with the first detector 17, and the switch 180, and thesecond detector 20, the third detector 220 may be disposed so that thefirst angle and the second angle differ from the third angle by apredetermined angle difference or less. In the second embodiment, thethird detector 220 is disposed so that the third angle as describedabove is 90°.

In the second embodiment, the third detector 220 is an active sensorthat detects reflected waves, from the object ob, of electromagneticwaves irradiated towards the object ob from the irradiator 12. The thirddetector 220 in the second embodiment detects reflected waves, from theobject ob, of electromagnetic waves irradiated towards the object obafter being irradiated from the irradiator 12 and reflected by thereflector 13. As described above, the electromagnetic waves irradiatedfrom the irradiator 12 are at least one of infrared light rays, visiblelight rays, ultraviolet rays, and radio waves, and the third detector220 detects the same or a different type of electromagnetic waves as thefirst detector 17 and the same type of electromagnetic wave as thesecond detector 20.

In greater detail, the third detector 220 of the second embodimentincludes a device configured as a ranging sensor. For example, the thirddetector 220 includes a single device such as an avalanche photodiode(APD), a photodiode (PD), a single photon avalanche diode (SPAD), amulti-pixel photon counter (MPPC), or a ranging image sensor. The thirddetector 220 may include a device array, such as a SPAD array, an APDarray, a PD array, a ranging imaging array, or a ranging image sensor.

The third detector 220 of the second embodiment transmits detectioninformation, indicating the detection of reflected waves from thesubject, to the controller 14 as a signal. In greater detail, the thirddetector 220 detects electromagnetic waves in the infrared light band.

It suffices for the single device configured as the above-describedranging sensor in the third detector 220 to be capable of detectingelectromagnetic waves. Image formation at the detection surface is notrequired. The third detector 220 therefore need not be provided at asecondary image formation position, which is a position of imageformation by the second post-stage optical system 210. In other words,as long as electromagnetic waves from all angles of view can be incidenton the detection surface, the third detector 220 with this configurationmay be disposed at any position along the path of electromagnetic wavesthat propagate in the fourth direction d4, due to the switch 180, andsubsequently pass through the second post-stage optical system 210.

In the second embodiment, unlike the first embodiment, the controller 14switches at least a portion of the switching elements se, in an imageformation region in the switch 180 where reflected waves from theirradiation region of electromagnetic waves are formed into an image bythe pre-stage optical system 15, to the first state, switches anotherportion of the switching elements se to the second state, and switchesthe remaining switching elements se to the third state.

In this way, the electromagnetic wave detection apparatus 100 of thesecond embodiment includes the third detector 220 that detectselectromagnetic waves propagated in the fourth direction d4 from theswitch 180. This configuration allows the electromagnetic wave detectionapparatus 100 to match the optical axis of the pre-stage optical system15 to the first propagation axis, which is the central axis of theelectromagnetic waves propagated in the first direction d1, to thesecond propagation axis, which is the central axis of theelectromagnetic waves propagated in the third direction d3, and to thethird propagation axis, which is the central axis of the electromagneticwaves propagated in the fourth direction d4. The electromagnetic wavedetection apparatus 100 can therefore reduce the misalignment of theoptical axes of the first detector 17, the second detector 20, and thethird detector 220. The electromagnetic wave detection apparatus 100 canthereby reduce the misalignment between the first detection axis, thesecond detection axis, and the third detection axis. Hence, theelectromagnetic wave detection apparatus 100 can reduce the misalignmentof coordinate systems in the detection results of the first detector 17,the second detector 20, and the third detector 220.

The electromagnetic wave detection apparatus 100 of the secondembodiment can switch a portion of the switching elements se in theswitch 180 to the first state and switch another portion of theswitching elements se to the second state. This configuration allows theelectromagnetic wave detection apparatus 100 to cause a portion of theswitching elements se to propagate electromagnetic waves towards thesecond detector 20 while causing another portion of the switchingelements se to propagate electromagnetic waves towards the thirddetector 220. The electromagnetic wave detection apparatus 100 cantherefore simultaneously acquire information relating to differentregions. In this way, the electromagnetic wave detection apparatus 100can shorten the time necessary for acquiring distance information inimage form, for example.

In the electromagnetic wave detection apparatus 100 of the secondembodiment, the third detector 220 is disposed, along with the switch180, relative to the separation unit 16 so that the third propagationaxis becomes parallel to the third detection axis. This configurationallows the electromagnetic wave detection apparatus 100 to reduce themisalignment between the first detection axis, the second detectionaxis, and the third detection axis and also achieve a uniform imagingstate of electromagnetic waves on the detection surface of the thirddetector 220, regardless of distance from the third propagation axis.Accordingly, the electromagnetic wave detection apparatus 100 can obtaininformation related to the surroundings in a uniform imaging statewithout performing information processing in the controller 14 toachieve a uniform imaging state.

In the electromagnetic wave detection apparatus 100 of the secondembodiment, the third detector 220 is disposed, along with the switch180, relative to the separation unit 16 so that the interval between thethird propagation axis and the third detection axis is equal to or lessthan the third interval threshold. This configuration allows theelectromagnetic wave detection apparatus 100 to reduce the misalignmentof the third detection axis relative to the first detection axis or thesecond detection axis further.

In the electromagnetic wave detection apparatus 100 of the secondembodiment, the first detector 17, the switch 180, the second detector20, and the third detector 220 are disposed relative to the separationunit 16 so that the interval between the third propagation axis and thethird detection axis differs from the interval between the firstpropagation axis and the first detection axis and the interval betweenthe second propagation axis and the second detection axis by apredetermined interval difference or less. This configuration allows theelectromagnetic wave detection apparatus 100 to reduce the misalignmentof the third detection axis relative to the first detection axis and thesecond detection axis even further.

In the electromagnetic wave detection apparatus 100 of the secondembodiment, the third detector 220, along with the switch 180, isdisposed relative to the separation unit 16 so that the thirdpropagation axis coincides with the third detection axis. Thisconfiguration allows the electromagnetic wave detection apparatus 100 toreduce the misalignment of the third detection axis relative to thefirst detection axis and the second detection axis even further still.

In the electromagnetic wave detection apparatus 100 of the secondembodiment, the third detector 220, along with the switch 180, isdisposed relative to the separation unit 16 so that the third angle isequal to or less than the third angle threshold or is a predeterminedangle. This configuration allows the electromagnetic wave detectionapparatus 100 to reduce the misalignment between the first detectionaxis, the second detection axis, and the third detection axis and alsoreduce the unevenness, corresponding to the distance from the thirdpropagation axis, of the imaging state of electromagnetic waves on thedetection surface of the third detector 220. Accordingly, theelectromagnetic wave detection apparatus 100 can reduce the burden onthe controller 14 for information processing to achieve a uniformimaging state.

In the electromagnetic wave detection apparatus 100 of the secondembodiment, the first detector 17, the switch 180, the second detector20, and the third detector 220 are disposed relative to the separationunit 16 so that the third angle differs from the first angle and thesecond angle by a predetermined angle difference or less. Thisconfiguration allows the electromagnetic wave detection apparatus 100 toreduce the misalignment of the optical axis of the third detector 220relative to the first detector 17 the second detector 20 even further.

Although the present disclosure has been explained using theaccompanying drawings and examples, it is to be noted that variouschanges and modifications will be apparent to those of ordinary skill inthe art based on the present disclosure. Therefore, such changes andmodifications are to be understood as included within the scope of thepresent disclosure.

For example, in the first embodiment and the second embodiment, theirradiator 12, the reflector 13, and the controller 14 form theinformation acquisition system 11 along with the electromagnetic wavedetection apparatus 10, 100, but the electromagnetic wave detectionapparatus 10, 100 may be configured to include at least one of thesecomponents.

In the first embodiment, the switch 18 can switch the propagationdirection of the electromagnetic waves incident on the action surface asbetween two directions, but the switch 18 may instead be capable ofswitching the propagation direction among three or more directions. Inthe second embodiment, the switch 180 can switch the propagationdirection of the electromagnetic waves incident on the action surface asamong three directions, but the switch 180 may instead be capable ofswitching among four or more directions.

In the switch 18 of the first embodiment, the first state is a firstreflecting state for reflecting the electromagnetic waves incident onthe action surface as in the third direction d3, and the second state isa second reflecting state for reflecting these electromagnetic waves inthe fourth direction d4. This configuration is not, however, limiting.

For example, as illustrated in FIG. 6, the first state may be atransmitting state for transmitting the electromagnetic waves incidenton the action surface so that the electromagnetic waves propagate in thethird direction d3. In greater detail, a switch 181 may include ashutter, on each switching element, that has a reflecting surface thatreflects electromagnetic waves in the fourth direction. The switch 181with this configuration can open and close the shutter of each switchingelement to switch each switching element between the transmitting statethat is the first state and the reflecting state that is the secondstate.

An example of the switch 181 with such a configuration is a switch thatincludes a MEMS shutter including a plurality of openable shuttersarranged in an array. Another example of the switch 181 is a switch thatincludes a liquid crystal shutter capable of switching, in accordancewith liquid crystal orientation, between the reflecting state forreflecting electromagnetic waves and the transmitting state fortransmitting electromagnetic waves. The switch 181 with thisconfiguration can switch each switching element between the transmittingstate as the first state and the reflecting state as the second state byswitching the liquid crystal orientation of each switching element.

In the first embodiment, the information acquisition system 11 isconfigured so that the reflector 13 scans the beam of electromagneticwaves emitted by the irradiator 12, thereby causing the second detector20 to works together with the reflector 13 and function as ascanning-type active sensor. In the second embodiment, the informationacquisition system 11 is configured so that the reflector 13 scans thebeam of electromagnetic waves emitted by the irradiator 12, therebycausing the second detector 20 and the third detector 220 to workstogether with the reflector 13 and function as a scanning-type activesensor. The information acquisition system 11 is not, however, limitedto this configuration. For example, the information acquisition system11 can achieve similar effects as in the first embodiment, withoutincluding the reflector 13, by causing electromagnetic waves to beemitted radially from the irradiator 12 and by acquiring informationwithout scanning.

In the information acquisition system 11 of the first embodiment, thefirst detector 17 is a passive sensor, and the second detector 20 is anactive sensor. The information acquisition system 11 is not, however,limited to this configuration. For example, similar effects as in thefirst embodiment can be achieved in the information acquisition system11 when the first detector 17 and the second detector 20 are both activesensors or both passive sensors. In the information acquisition system11 of the second embodiment, the first detector 17 is a passive sensor,and the second detector 20 and third detector 220 are active sensors.The information acquisition system 11 is not, however, limited to thisconfiguration. For example, similar effects as in the second embodimentcan be achieved in the information acquisition system 11 when the firstdetector 17, the second detector 20, and the third detector 220 are allactive sensors or all passive sensors. Furthermore, similar effects asin the second embodiment can be achieved in the information acquisitionsystem 11 when any two of the first detector 17, the second detector 20,and the third detector 220 are passive sensors.

While the disclosed system has a variety of modules and/or units forimplementing particular functions, these modules and units have onlybeen indicated schematically in order to briefly illustrate thefunctionality thereof. It should be noted that no particular hardwareand/or software is necessarily indicated. In this sense, it suffices forthe modules, units, and other constituent elements to be hardware and/orsoftware implemented so as to substantially execute the particularfunctions described herein. The various functions of differentconstituent elements may be implemented by combining or separatinghardware and/or software in any way, and the functions may each be usedindividually or in some combination. An input/output (I/O) device oruser interface including, but not limited to, a keyboard, display,touchscreen, or pointing device may be connected to the system directlyor via an I/O controller. In this way, the various subject matterdisclosed herein may be embodied in a variety of forms, and all suchembodiments are included in the scope of the subject matter in thepresent disclosure.

REFERENCE SIGNS LIST

-   -   10, 100 Electromagnetic wave detection apparatus    -   11 Information acquisition system    -   12 Irradiator    -   13 Reflector    -   14 Controller    -   15 Pre-stage optical system    -   16 Separation unit    -   17 First detector    -   18, 180, 181 Switch    -   19 First post-stage optical system    -   20 Second detector    -   210 Second post-stage optical system    -   220 Third detector    -   as Action surface    -   d1, d2, d3, d4 First direction, second direction, third        direction, fourth direction    -   ob Object

The invention claimed is:
 1. An electromagnetic wave detection apparatuscomprising: a separation unit configured to separate electromagneticwaves incident on the separation unit so that the electromagnetic wavespropagate in a first direction and a second direction; a first detectorconfigured to detect the electromagnetic waves that propagate in thefirst direction; a switch comprising a plurality of switching elementscapable of switching between a first state and a second state, theelectromagnetic waves that propagate in the second direction beingcaused to propagate in a third direction in the first state and theelectromagnetic waves that propagate in the second direction beingcaused to propagate in a fourth direction in the second state; and asecond detector configured to detect the electromagnetic waves thatpropagate in the third direction, the switch switching each of theplurality of switching elements between the first state and the secondstate in accordance with an irradiation region with electromagneticwaves that are emitted by an irradiator.
 2. The electromagnetic wavedetection apparatus of claim 1, further comprising a third detectorconfigured to detect the electromagnetic waves that propagate in thefourth direction.
 3. The electromagnetic wave detection apparatus ofclaim 1, wherein the separation unit is configured to reflect a portionof the electromagnetic waves incident on the separation unit in thefirst direction and transmit another portion of the electromagneticwaves in the second direction.
 4. The electromagnetic wave detectionapparatus of claim 1, wherein the separation unit is configured totransmit a portion of the electromagnetic waves incident on theseparation unit in the first direction and transmit another portion ofthe electromagnetic waves in the second direction.
 5. Theelectromagnetic wave detection apparatus of claim 1, wherein theseparation unit is configured to refract a portion of theelectromagnetic waves incident on the separation unit in the firstdirection and refract another portion of the electromagnetic waves inthe second direction.
 6. The electromagnetic wave detection apparatus ofclaim 1, wherein the switch comprises a digital micro mirror device. 7.The electromagnetic wave detection apparatus of claim 1, wherein theswitch is configured to switch each switching element between atransmitting state of transmitting the electromagnetic waves thatpropagate in the second direction towards the third direction and areflecting state of reflecting the electromagnetic waves that propagatein the second direction towards the fourth direction.
 8. Theelectromagnetic wave detection apparatus of claim 1, further comprisinga controller configured to acquire information related to surroundingsbased on an electromagnetic wave detection result by the first detectorand the second detector.
 9. The electromagnetic wave detection apparatusof claim 8, wherein the controller is configured to acquire at least oneof image information, distance information, and temperature informationas the information related to the surroundings.
 10. An informationacquisition system comprising: an electromagnetic wave detectionapparatus comprising a separation unit configured to separateelectromagnetic waves incident on the separation unit so that theelectromagnetic waves propagate in a first direction and a seconddirection, a first detector configured to detect the electromagneticwaves that propagate in the first direction, a switch comprising aplurality of switching elements capable of switching between a firststate and a second state, the electromagnetic waves that propagate inthe second direction being caused to propagate in a third direction inthe first state and the electromagnetic waves that propagate in thesecond direction being caused to propagate in a fourth direction in thesecond state, and a second detector configured to detect theelectromagnetic waves that propagate in the third direction; and acontroller configured to acquire information related to surroundings ofthe electromagnetic wave detection apparatus based on an electromagneticwave detection result by the first detector and the second detector, theswitch switching each of the plurality of switching elements between thefirst state and the second state in accordance with an irradiationregion with electromagnetic waves that are emitted by an irradiator. 11.The electromagnetic wave detection apparatus of claim 1, wherein theswitch is configured to switch a switching element that corresponds tothe irradiation region to the first state and another switching elementto the second state among the plurality of switching element.
 12. Theelectromagnetic wave detection apparatus of claim 1, wherein the switchis configured to switch each of the plurality of switching elementsbetween the first state and the second state in accordance with a targetarea to be detected in the irradiation region.
 13. The electromagneticwave detection apparatus of claim 1, further comprising a changerconfigured to change the irradiation region; wherein the switch isconfigured to switch each of the plurality of switching elements betweenthe first state and the second state in accordance with a change of theirradiation region by the changer.
 14. The electromagnetic wavedetection apparatus of claim 1, further comprising an image formerconfigured to forms an image of electromagnetic waves that propagate inthe second direction; wherein the switch is provided at or near an imageformation position of the image former.
 15. The electromagnetic wavedetection apparatus of claim 1, wherein the first detector is an imagesensor for generating an image information of an object captured withincident electromagnetic waves; and wherein the second detector includesa device configure as a ranging sensor for measuring a distance to theobject irradiated with the electromagnetic waves that are emitted by theirradiator.
 16. The electromagnetic wave detection apparatus of claim 1,wherein the first detector is configured to detect visible light rays,and the second detector is configured to detect infrared rays.
 17. Theelectromagnetic wave detection apparatus of claim 1, further comprisingan irradiation-direction-changer configured to change the irradiationregion by changing an irradiation direction of electromagnetic wavesemitted by the irradiator; wherein the switch is configured to switcheach of the plurality of switching elements between the first state andthe second state in accordance with the irradiation region.
 18. Theelectromagnetic wave detection apparatus of claim 1, further comprisingan image former configured to forms an image of electromagnetic wavesthat propagate in the second direction; wherein the switch is configuredto switch at least a part of a switching element, in an image formedregion where the image former forms an image of incident electromagneticwaves from the irradiation region, to the first state and anotherswitching element to the second state among the plurality of switchingelement.
 19. The electromagnetic wave detection apparatus of claim 1,wherein the first detector is disposed so that a first propagation axisis parallel to a first detection axis, the first propagation axis is acentral axis of the electromagnetic waves that propagate from theseparation unit in the first direction, and the first detection axispasses through a center of a detection surface where the first detectordetects electromagnetic waves and is perpendicular to the detectionsurface; and wherein the switch and the second detector are disposed sothat a second propagation axis is parallel to a second detection axis,the second propagation axis is a central axis of the electromagneticwaves that propagate from the separation unit in the second directionand are switched in propagation direction to the third direction by theswitch, and the second detection axis passes through a center of adetection surface where the second detector detects electromagneticwaves and is perpendicular to the detection surface.
 20. Theelectromagnetic wave detection apparatus of claim 1, wherein the firstdetector is disposed so that a first angle between a central axis of theelectromagnetic waves that propagate from the separation unit in thefirst direction and a detection surface of the first detector is equalto or less than a first angle threshold or is a predetermined angle; andwherein the switch and the second detector are disposed so that a secondangle between a central axis of the electromagnetic waves that propagatefrom the separation unit in the second direction and are switched inpropagation direction to the third direction by the switch and adetection surface of the second detector is equal to or less than asecond angle threshold or is a predetermined angle.